The 2015 Moto X Pure Edition has only been out for a few months at this point, but a new leak purports to show off its successor. The device posted on Nowhere Else (a French site) has a metal back with Motorola branding and a gigantic camera module. It doesn't look like a finished product, but phone development cycles are notoriously long.
We only see this device from the back, so there's only so much that can be gleaned from one image. The construction appears to be metal, whereas previous Moto X devices have been plastic, wood, and leather on the back. Toward the bottom of the back is what looks like a speaker grille. Again, that would be strange for the Moto X as the current one has front-facing stereo speakers.
You can also see three buttons along the side—presumably power, volume up, and volume down. They are all about the same size and equally spaced, which as we learned from the HTC One M9, is a very bad idea. The camera module is huge too. This is the part that really makes me question the accuracy of this leak. It could totally be a Motorola engineering sample, but I'd be shocked to see anything like this ship next year.